In wireless communication systems, MIMO (multiple input, multiple output) antenna systems can significantly increase the data carrying capacity of wireless systems. For these reasons, MIMO is an integral part of third and fourth generation wireless systems. Fifth generation (5G) access networks, which can also be referred to as New Radio (NR) access networks, will also employ MIMO systems, called massive MIMO systems (having on the order of hundreds of antennas at the Transmitter side and/Receiver side). With an (Nt,Nr) MIMO system, where Nt denotes the number of transmit antennas and Nr denotes the receive antennas, the peak data rate multiplies with a factor of Nt over single antenna systems in a rich scattering environment.
While MIMO provides many benefits, the performance of conventional MIMO systems degrades under certain conditions, including at high user equipment speeds. More particularly, when a mobile device moving at high speeds, the receiver of a signal is moving in relation to the transmitter, resulting in the Doppler effect because the frequency of the signal is shifted, such that it is perceived to be different at the receiver than at the transmitter. The performance degradation is severe when the signal to noise ratio (SNR) is high. If the rank in transmission is high, it is also the case that the SNR is high. For high rank systems, the impact due to mismatch between the transmitter and receiver channel qualities is severe.